| Roughage was a component of ruminant dietary, and was an indispensable ingredient for catties and sheeps. Different roughage sources and different animal species were two important factors to affect the nutritional value. In this paper, the nutritional value of different sources of roughage were evaluated by in vitro methods and in situ methods for sheep. Three emasculated Dorper×Han crossbred male sheep of similar body weight (65+1.0kg) fitted with permanent rumen fistula were selected in this experiment. With the same feeding level, degradation rules of50roughages were investigated in nylon-bag technique. Ruminal degradability and parameters of DM, OM, CP, NDF were calculated, and the ruminal outflow rates of5representative roughages were measured actually.1. The collection and basic nutrient analysis of rouragesThe differences with general nutrients of50roughages (24forages,22staws,4dregs) were determined by Weende analysis, the results showed as follows:there was a negative correlation between CP content and NDF, NDF, there were great differences in protein and fiber materials contents of same type of roughages. The nutrition qualities of legume forage were better than others. The nutrition qualities of gramineae forages corn grass, Pennisetum purpureum, Poa pratensis were better, vine staws were better than crop straws; silage maize straws, millet straws and naked oats grass were also better.2. Ruminal degradability characteristics of different forages in sheepIn order to investigate dry matter (DM) and protein (CP) degradation rules of different forages, ruminal degradability of13forages were estimated The results showed as follows:ruminal degradability at various time points of DM and CP of Medicago sativa were highest; Astragalus adsurgens, Setaria viridis, Arrhenatherum elatius and Poa pratensis were significantly higer than others at72hour (P<0.05). For13forages, potential degradation part and effective degradability of DM showed the similar change law with degradability at various time points of DM. CP effective degradability of leguminosae Medicago sativa and Astragalus adsurgens were highest; gramineae Arrhenatherum elatius, Pennisetum purpureum, Poa pratensis and Setaria viridis were significantly higer than others (P<0.05). The rate constant for the slow degradation part of Medicago sativa was significantly higher than other forages (P<0.05). In conclusion, DM and CP ruminal degradability of leguminosae Medicago sativa and Astragalus adsurgens were higher man gramineae pasture; gramineae Arrhenatherum elatius, Poa pratensis, Pennisetum purpureum and Setaria viridis were higher than other7forages; Poa crymophila, Elymus sibiricus, Leymus chinensis and Elymus dahuricus were in the middle; Achnatherum splendens, Festuca sinensis and Phragmites australis were low.3. Ruminal degradability characteristics of different kinds of crop straw in sheepThis chapter was conducted to investigate ruminal degradation rules of different kinds of crop straw in sheep, DM and NDF ruminal degradabiliry and parameters of19crop straw of7species were estimated, and silage maize straws were as control group. The results showed as follows:the ruminal degradation of DM and NDF were similar among straws, and the degradability was unchanged after48h. Ruminal degradability at72hours and effective degradation (ED) of sweet potato vine and peanut vine were highest, which were close to corn silage, while that of corn straw, soybean straw and rice straw were lower, and wheat straw was lowest (P<0.05). There was a strong correlation between the effective degradation of DM, NDF and CP, NDF, ADF (P<0.04):DMD=0.9900+0.3270CP-0.8099NDF-0.1880ADF (R2=0.8860, P<0.0001); NDFD=0.5111+0.3833CP-0.1519NDF-0.3963ADF (R2=0.7585,P<0.0001). Sweet potato vine and peanut vine had higher degradation rate in the rumen, which are reasonable feed sources for sheep. By contrast, corn straw, soybean straw, rice straw and wheat straw had poor degradation rate.4. The determination about ruminal outflow rate of five roughagesThis experiment was conducted to investigate the ruminal outflow rates of different roughages particles (chinese wildrye hay, wheat straw, alfalfa, sweet potato vine, corn stalk) in sheep. Five roughages were mordanted by potassium dichromate solution, flame atomic absorption spectrometry was used to determine chromium content of fecal samples,and the ruminal outflow rates of five roughages were calculated with mathematical model. The results showed as follows:chromium in different mordanted forage were expelled from feces at different crest-time and focused on the20-28h.There were significant differences in the outflow rate of different roughages (P<0.05), k value of Chinese wildrye hay,wheat straw, alfalfa, sweet potato vine and corn stalk were3.92,3.07,4.30,4.63and3.16%/h, respectively.There was a strong correlation with the crude protein content of feed ingredients (R2=0.9035, P=0.0131).The different feeds have different outflow rates from rumen. K value in this research can be used as outflow rates of rumen reference for the related kinds of roughages.5. Comparative study on investigate of different k valuesIn order to investigate the differences of ruminal degradation rules, degradabilities of DM, CP, NDF of 11roughages (4forages and7crop by-products) were determined, and contrast differences of degradation of cited value k with actual measured value k. The results showed as follows:degradation of actual measured value k were lower than cited value k, DM, CP, NDF of Alfalfa were highest (P<0.05), for the same kind of Green bristlegrass, degradation of Green bristlegrass1was higher than Green bristlegrass2(P<0.05), Mung bean straw and Pinto bean straw were higer than Highland barley straw (P<0.05). In conclusion, ruminal degradability of Alfalfa, Naked oats grass, Millet grass, corn grass were higer, and were better quality roughages; the nutritional qualities of Chinese wildrye, Sorghum grass, Mung bean straw, Pinto bean, Green bristlegrass1were ordinary; ruminal degradability of Green bristlegrass2and Highland barley straw were lower, and need be improved digestibility by further processing.6. The prediction models of ruminal effective degradationThe relationship with ruminal effective degradabilitis and nutrient components were determined, statistical datas were analysed by simple correlation and fitting program in SAS9.1,the results showed as follows:there was a positive correlation between DMD, OMD, CPD, NDFD and CP, a negative correlation between DMD, OMD, CPD, NDFD and NDF, ADF. The prediction models of DMD, OMD, CPD, NDFD in different k values were calculated. With k value in this study:DMD=92.6665+0.1135CP-0.6366NDF-0.3506ADF (R2=0.8484); OMD=82.3659+0.1907CP-0.4834NDF-0.3867ADF (R2=0.7329); CPD=58.9750+1.8193CP-0.3527NDF-0.1248ADF (R2=0.6398); NDFD=50.0615+0.2483CP-0.3092NDF-0.2201ADF (R2=0.6601)。... |
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